<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8"/>
        <title>
            Document
        </title>
        <style>
                *{
                    margin:0 ;
                    padding:0;
                }
                .layout{

                    width:1200px;
                    height:1000px;
                    background-color: pink;
                }
                .clearfix::before{
                    content:'';
                    display:block;
                    visibility:hidden;
                    clear:both;
                }
                .clearfix{
                    *zoom:1;
                }
                .left{
                    float: left;
            width:300px;
            height:100%;
            background-color: green;
                }
                .center{

                    margin-left:300px;
                    margin-right:300px;
                    height:100%;
                    background-color: yellow;
                }
                .right{
                    float: left;
                    width:300px;
                    height:100%;
                    background-color: blue;
                }
                </style>
    </head>
    <body>
        <!-- ## 假设高度已知，请写出三栏布局，其中左栏、右栏宽度各为300px，中间自适应。 -->
        <div class="layout clearfix">
            <div class="left"></div><div class="right"></div><div class="center"></div>
        </div>
    </body>
</html>
